Unfortunately, there is no doubt that the vast majority of the images of coalition troops subjecting Iraqi prisoners to degrading treatment revealed recently are all too genuine. But at the time of writing, the authenticity of one of the first batch to appear remains in doubt. Experts have provided many reasons for thinking that the images of British troops mistreating prisoners published in the Mirror may be fakes.

If they are not genuine, this would be no small blunder. The perception that maltreatment is going on fuels Iraqi resentment of the occupying forces and helps the cause of the “resistance”. Although subsequent revelations have confirmed that mistreatment is occurring anyway, the veracity of the Mirror images would significantly alter the evidence of the extent to which British troops are contributing to it.

So it would seem a fair question to ask: if the images are fakes, will the Mirror’s editor have to resign? Blank and Bailey, however, both refused to answer it, on the grounds that it was a purely hypothetical question.

Nigel Warburton, in his Thinking From A to Z , dubbed this the “politician’s answer”, with good reason. It has become a favoured tool of evasion for politicians the world over, who often bat away queries saying, “that’s a hypothetical question”.

However, look for a justification for the assumption that only questions about what is actual need to be answered and you’ll search in vain. Indeed, it is ironic that politicians are so keen to avoid hypothetical questions when their entire campaigns are run on the basis of hypotheticals: if you elect me, I’ll do this. If they truly believed that they shouldn’t answer hypothetical questions, then they should refrain from saying anything about what they would do if they gained power.

There are good reasons why it is sometimes unwise to answer hypothetical questions. One is that it is often not worth worrying about all the possible things that might happen. You have to weigh up the probabilities and the seriousness of the consequences to decide whether in any given case “We’ll cross that bridge when we come to it” betrays a shocking lack of forethought (the plan for what to do in Iraq once Saddam had been toppled is a clear contender for this category) or a prudent conservation of intellectual energy (for instance, how to save tax in the 14 million to one chance that you win the lottery).

Another is that circumstances change, and it can be unwise to commit yourself to a future course of action when unforeseen events may change the calculations about what the best course of action is. For example, before the Iraq war, Tony Blair frequently dodged the question of what he would do if there was no “second” UN resolution backing military action against Iraq . In this case, the existence or not of an UN resolution was just one of a number of factors which would contribute to his eventual decision. With events on the ground changing every day, unless you thought military action without UN backing was unjustifiable in all circumstances (in which case you would have to be opposed to the NATO action in former Yugoslavia and British intervention in Sierra Leone), Blair could not predict the eventual weighting the resolution, or lack of it, should have in his deliberations.

But it is important to note that the problem here is not that the question about UN backing was hypothetical. It is rather that there were so many other variables that there was no single hypothetical scenario in which UN backing was not forthcoming for Blair to comment on. Rather, there were any number of different scenarios consistent with that outcome, not all of which could even be foreseen, and all of which would have to be judged on their merits. Only if one already thought that the requirement for a UN resolution was absolute, which would make all the different scenarios identical in the one regard that mattered, could the hypothetical question be answered.

In Morgan’s case, however, this justification for evasion does not seem to apply. It is true that there are many scenarios consistent with the pictures being fakes. But in all cases, publishing fakes would be a terrible error and one which, arguably, the editor of the paper involved should take responsibility for. That means the hypothetical question is both clear and could be answered. The fact that the Mirror ‘s chiefs chose not to cannot be justified by the hypothetical nature of the question, because the mere fact that a question is hypothetical is never a reason why it can’t or shouldn’t be answered.